Can you imagine sitting on a surfboard, in a kayak or being out scuba diving and looking down to see the silhouette of a 20-foot great white shark pass under you?

Among the scariest possibilities in the outdoors in California, that has to be the most petrifying.

The great whites seem to have a thing this year about "test bites," as well as occasional full-on attacks on humans.

Off Eureka last week, a big shark grabbed a surfer and pulled him underwater. The surfer, Scott Stephens, 25, said he punched the shark in the nose, and it released him. Stephens is recovering after surgery for seven deep lacerations.

The week before, another surfer, this one near Santa Barbara, died after an attack by a shark reported to be 15 to 16 feet long.

This summer, a kayak angler out of Santa Cruz escaped after his boat was munched a quarter mile off Pleasure Point, a spot where I've taken surfing lessons. In July, off Topanga Beach near Los Angeles, a big shark knocked a teenager off his surfboard. In May, a girl on a paddleboard was attacked at Catalina Island but escaped when the shark took a "test bite" and got plastic, not flesh.

That's an average of about one attack per month on the California coast.

Tracking studies show the big sharks often loom in the highest numbers off the Bay Area coast in November. I love kayaking, surfing and scuba diving, but you won't find me dressing up like a sea lion and dangling my legs in the water anytime soon.

With a shark attack leading the list, here are the 10 scariest scenarios in the outdoors in California:

1. Great white menace: I've seen the big sharks do their thing. Like picking a 600-pound sea lion out of the surf line, surging into the air with it like a dog shaking a bone, then biting it in half. To see one cruise past my boat at close range and give me the eye, as if sizing me up for an easy three-bite meal, was terrifying. Problem is, they don't think. They see, react and chomp, influenced by 400 million years of evolution.

2. A river wild: Mountains wait for you to make a mistake, but rivers claw at you like wild banshees. Try fording a high river without a safety rope and tumbling, or fly fishing the edge of whitewater and slipping, or getting dumped rafting in Class V rapids without a pro around to pull you out. You feel utterly helpless being carried downstream, where you look up and see the river surface - and air - just above you, but out of reach. Been there, my friends.

3. Charging wild cow: I've been charged by grizzly bears in Alaska and wild boar in the foothills and have had several point-blank stare-downs with mountain lions. At least they can think. None of those showdowns compare to running into a nasty, pea-brained wild cow that will run over the top of you. I've had encounters with wild cows in the remote foothills of Lassen, up Mill Creek and Paynes Creek. They are like a mutant creation from a failed lab experiment in an old science fiction film.

4. Big ocean, small boat: You're out to sea, far offshore, when fog reduces visibility to zero and you try to get back to harbor amid huge swells with a following sea, with breakers at the crest from a 30-knot south wind. A nightmare. At the bottom of the trough, if you get turned sideways, over you go, and there's no finding you anytime soon.

5. Disturbing hornets' nest: When you scramble off trail up a wooded wilderness canyon, you can step on, or put your hand on, a hornets' nest embedded in the ground. The swarm will "mark" you by your scent and then sting you over and over, in the head, neck, back, arm and butt. You might try to run, but you can't hide.

6. Ridge hopping, wet shale: Off trail in wilderness, you can roam up and down the ridges and eventually might get caught in a thunderstorm. On wet shale on the ridges, you need to be a mountain goat to avoid a slip and a 1,000-foot fall.

7. Kaiser Pass Road: From Huntington Lake in the west Sierra, Kaiser Pass Road is a narrow, cliff-edged route to Mono Hot Springs and the fork to Edison Lake and Florence Lake. Problem is, insanity reigns from deranged L.A. drivers, who speed through blind turns on Friday evenings on the way in and Sunday afternoons on the way back. Try towing a boat here, and it's Russian roulette.

8. Mama elk: The big bull elk have antlers that poke holes in the sky, but it's the mama elk with their young that will plow you over. On a trail at Prairie Creek Redwoods last year, we had to jump over a log and down a canyon to avoid getting thrashed.

9. Flash flood in desert: Never camp in a gully, draw or near a creek in the desert. Short intense rains can collect in pools, then bust through and head down a canyon like a tidal wave and wash you away. In your tent in a storm, you'll never see it coming.

10. Irritated rattlesnake: Just don't step on them, right? So far, I've avoided this, despite several close calls - like inches from direct hits with my size-13 Vibrams. But many of my pals have not. One buddy reached for a camera and found himself shaking hands with Mr. Rattler. A few others were victims of bull's-eye strikes while hiking. Out come the fangs. Off to the hospital you go.